Process for preparing vulcanized epihalohydrin polymers

ABSTRACT

A PROCESS FOR PREPARING VULCANIZED EPIHALOHYDRIN POLYMERS WHICH COMPRISES HEATING AT LEAST A POLYMER SELECTED FROM THE GROUP CONSISTING OF A HOMOPOLYMER OF EPIHALOHYDRIN AND A COPOLYMER OF EPIHALOHYDRIN WITH AT LEAST ONE OTHER COPOLYMERIZABLE MONOMER IN THE PRESENCE OF (A) 0.1-10 PARTS BY WEIGHT OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF POLYALKYLENEPOLYAMINES, POLYALKYLENEPOLYAMINE CARBAMATES AND THIOUREAS WHICH ARE OPTIONALLY SUBSTITUTED WITH ALKYL GROUPS OF 1-4 CARBON ATOMS LEAVING AT LEAST ONE HYDROGEN ATOM UNSUBSTITUTED, (B) 1-20 PARTS BY WEIGHT OF MAGNESIUM OXIDE AND (C9 0.2-5 PARTS BY WEIGHT OF 2-MERCAPTOBENZIMIDAZOLE.

United States Patent US. Cl. 260-453 N 8 Claims ABSTRACT OF THEDISCLOSURE A process for preparing vulcanized epihalohydrin polymerswhich comprises heating at least a polymer selected from the groupconsisting of a homopolymer of epihalohydrin and a copolymer ofepihalohydrin with at least one other copolymerizable monomer in thepresence of (A) 0.1-10 parts by weight of at least one compound selectedfrom the group consisting of polyalkylenepolyamines,polyalkylenepolyamine carbamates and thioureas which are optionallysubstituted with alkyl groups of l-4 carbon atoms leaving at least onehydrogen atom unsubstituted, (B) 120 parts by weight of magnesium oxideand (C) 0.2-5 parts by weight of Z-mercaptobenzimidazole.

This invention relates to a process for preparing vulcanizedepihalohydrin homopolymers or copolymers with a novel system ofvulcanizing agents.

Vulcanized epihalohydrin polymers have been prepared by conventionalmethods with such vulcanizing agents as polyamines (U.S. Pat.3,026,270), an amine and at least one other agent selected from thegroup consisting of sulphur, dithiocarbamates, thiuram sulfides andthiazoles (U.S. Pat. 3,026,305), or Z-mercaptoimidazolines withcompounds of Groups II or IV-A metals of periodic table (U.S. Pat.3,341,491). Further, it is known that stabilized epihalohydrin polymercompositions are prepared with a polyamine cross-linking agent, a leadcompound and a nitro-containing antioxidant (U.S. Pat. 3,239,486).

As a result of various studies on the heat-aging properties ofvulcanized epihalohydrin polymers manufactured by the use of suchvulcanizing agents and antioxidants, the inventors have found that avulcanizate containing Z-mercaptoimidazoline, red lead and phenoloraminebased antioxidants which are employed for ordinary diene rubberexhibits good heat-aging property. When a thiourea or an amine isemployed in place of Z-mercaptoimidazoline and when magnesium oxide isused instead of red lead, the vulcanizate obtained shows obviouslyinferior heat-aging properties with an increased tendency towardsoftening and aging, which will be clarified by reference examples givenbelow. However, applications of the vulcanizate are limited as thevulcanizate cannot be used for light-color blending because it containsred lead having staining qualities and also because it often takes on ametallic luster on its surface. Furthermore, since red lead tends tostain the mold, work required to remove such stains decreases theproductivity.

The purposes of this invention, therefore, are to resolve all thoseproblems and to produce vulcanized epihalohydrin polymers havingexcellent heat-aging properties.

The above purposes of this invention can be attained by the processwhich comprises heating a homopolymer of epihalohydrin or a copolymer ofepihalohydrin with at least one other copolymerizable monomer in thepresence of (A) at least one compound selected from the group 3,790,524Patented Feb. 5, 1974 ice consisting of polyalkylenepolyamines,polyalkylenepolyamine carbamates and thioureas which are optionallysubstituted with alkyl groups of 1-4 carbon atoms leaving at least onehydrogen atom unsubstituted, (B) magnesium oxide and (C)2-mercaptobenzimidazole.

By the process of this invention, vulcanized epihalohydrin polymers withexcellent heat-aging properties which are equivalent or superior to thatwhich can be attained by the Z-mercaptoimidazoline/red lead vulcanizingsystem, and with limited staining properties enabling light-colorblending, can be prepared.

, A feature of this invention consists in the joint use of magnesiumoxide and Z-mercaptobenzimidazole. Namely, whereas in the case of theconventional combination of vulcanizing agents and anti-oxidants, theheat-aging properties of a vulcanizate with magnesium oxide is inferiorto that of vulcanizate with red lead. In the cases wherepolyalkylenepolyamines or their carbamates or thioureas and red lead ormagnesium oxide and 2-mercaptobenzimidazole are employed jointly, thevulcanizate with magnesium oxide provides improved heat-agingproperties. Although it is not yet clear what mechanism causes such anotable phenomenon, it is probably attributable to some multiplyingeffects caused by the coexistence of 2-mercaptobenzimidazole andmagnesium oxide. Further studies by the inventors on the properties ofZ-mercaptobenzimidazole have revealed that it has little antioxidizingproperties unlike the amineor phenol-based antioxidants in general use.For instance, it was found that its speed of oxygen absorption whenuniformly dispersed in an epichlorohydrin polymer in a quantity of 2percent by weight of said polymer, was 40 times that ofphenyl-fl-naphthylamine and 12 times that of styrenated phenol.

Furthermore, in this invention, magnesium oxide is employed as co-agent,and therefore the aforementioned various problems which are caused bythe use of red lead can be completely avoided.

The epihalohydrin polymers vulcanizable in accordance with thisinvention comprise homopolymers of epichlorohydrin and/orepibromohydrin, copolymers of two different epihalohydrins, andcopolymers of at least one epihalohydrin with at least one othercopolymerizable monomer. Examples of other copolymerizable monomersinclude epoxides such as ethylene oxide, propylene, pr0- pylene oxide,butylene oxide, cyclohexene, oxide, butadiene monoxide, ethyl glycidylether, allyl glycidyl ether, tetrahydrofuran and trioxane; isocyanatessuch as ethyl isocyanate, phenyl isocyanate and 2,4-tolylenediisocyanate; alkyl acrylates such as ethyl acrylate and methylmethacrylate; cyclic acid anhydrides such as maleic anhydride, succinicanhydride and phthalic anhydride; vinyl ketones such as methyl vinylketone and cyclohexyl vinyl ketone; diolefins such as butadiene,isoprene and pentadiene; monoolefins such as ethylene, propylene andbutene-l; nitriles such as acrylonitrile and methacrylonitrile; andstyrene.

Of the agents used for vulcanizing those epihalohydrin polymers in thisinvention, diethylenetriamine, triethylenetetramine,hexamethylene-diamine, hexamethylenetetraamine, piperazine (a cyclicpolyalkylenepolyamine) and Trimene Base (trademark of Uniroyal, Inc.),hexamethylenediamine, carbamate and ethylene-diamine carbamate arerepresentative examples of polyalkylenepolyamines and their carbamatesof (A). Another example pertaining to (A) is thioureas with thefollowing general formula:

wherein at least one of the R's is hydrogen, and the rest are alkylgroups of 1 to 4 carbons and whose representative examples are thiourea,mono-, dior tri-ethyl thiourea and mono-, dior tri-butyl thiourea.

Z-mercaptobenzimidazole of (C) is an agent which is represented by thefollowing formula:

and therefore, Z-mercaptobenzimidazole functions entirely differently inthe respective cases. As clearly shown by the following examples, theheat-aging property can be drastically improved by the presentinvention.

it is sometimes heated at approximately 100 to 150 C. for about 1 hourto three days.

In addition to the aforementioned agents, other ordinary agents such asreinforcing agents, fillers, softening agents, plasticizers,stabilizers, activating agents and other anti-oxidants may be added asnecessary.

This invention will be explained in greater detail by means of thefollowing examples. Parts of components to be compounded in the exampleswill be shown by weight.

EXAMPLES 1-8 To various conventional vulcanizing agents andantioxidants, red lead or magnesium oxide was added as a co-agent, andcomparison was made on the effects caused to heat-aging properties byeach one of the above-mentioned coagents. After the components shown inTable 1 were kneaded together on 6-inch rolls at 30 to 40 C. and forapproximately 30 minutes, the mixed compounds were vulcanized at 155 C.for 30 minutes. Then the heat-aging properties of the obtainedvulcanizate (JIS K- 6301, heating temperature: 150 C.) were measured. Itis obvious from the results given in Table 1 that when the conventionalvulcanizing agent and the antioxidant are combined, in each case, redlead is superior to magnesium oxide in improving the heat-agingproperty.

TABLE 1 Example Compounding components:

Epichlorohydrin polymer 1 100 100 100 100 100 100 100 100 Tin stearate 22 2 2 2 2 2 2 FEF carbon black. 40 40 40 40 40 40 4O 40Phenyl-B-naphthylarmne 1. 5 1. 4 1. 5 1. 5 1. 5 1. 5 1. 5 1. Nickeldibutyl dithmcarbamata- 0. 0. 5 0. 5 0. 5 0. 5 0. 5

Magnesium oxide 5 Heat-aging properties of the vuleanizates:

Tengiilizstrength (kg/em!) after- 9 days Hargress (J IS) afte 166 81 i731 112 so ss 10 s 62 7 s 14 s s s 260 430 250 s 310 s s s s5 s9 e5 e1 1574 71 75 '27 as 67 56 so as 7s 68 74 66 54 s 73 s as s 7-1 as 51 8S lGeehron 1000 made by The Japanese Geon Co. (hereinafter the same).

I Dial: No. 1 made by Du Pont (hereinafter the same).

8 8" denotes that the vulcanrzates softened and aged (hereinafter thesame). No heat-aging (hereinafter the same).

In this invention, quantities of the three agents for each 100 parts byweight of epihalohydrin polymers are as follows: thioureas,polyalkylenepolyamines or polyalkylenepolyamine carbamates 0.1-10(preferably 0.5-4) parts by Weight, magnesium oxide 1-20 (preferably3-10) parts by weight, and Z-mercaptobenzimidazole 0.2-5 (preferably0.4-2) parts by weight.

The purpose of the present invention may be essentially attained byheating epihalohydrin polymers in the presence of the above-mentionedthree components. Furthermore, by employing sulphur jointly, the tensilestrength of the vulcanizates under normal conditions and afterheat-aging may be even more improved. Volume of sulphur to be used is0.1-5 (preferably 0.5-2) parts by weight against 100 parts of thepolymer by weight.

Vulcanization in this invention may be attained by heating the polymerafter being compounded with the aforementioned agents by ordinarymethods such as roll mixing, Banbury mixing or solution mixing.Vulcanizetion temperature will be approximately 120 to 180 C. andvulcanization time 10 to 120 minutes. Furthermore, in order to minimizepermanent set at high temperatures,

EXAMPLES 9-18 A comparison was made as to the effects caused onheat-aging property when either magnesium oxide or red lead was added tohexamethylenediamine carbamate and Z-rnercaptobenzimidazole.Furthermore, effects of volume change by 2-mercaptobenzimidazole werestudied. Heataging properties (heating temperature: C.) of vulcanizateswhich were obtained in the same manner as in Examples 1-8 are indicatedin Table 2. Added for reference are the case ofZ-mercaptoimidazoline/red lead as a representative known vulcanizingagent and the case where Z-mercaptobenzothiazole is employed in place of2-mercaptobenzimidazole of this invention. As the results in Table 2show, the heat-aging property of the vulcanizates can be improved byincreasing the amount of 2-mercaptobenzimidazole in both systems. It isseen that at any level of consumption of Z-mercaptobenzimidazole,magnesium oxide system is superior and that the effects of usingincreased amount of Z-mercaptobenzimidazole are greater in this system.It is also seen that in comparison with the Z-mercaptoimidazoline/redlead system, magnesium oxide system presents, at 0.8 part or more byWeight, equal or improved heat-aging properties. It is obvious,furthermore, that when Z-mercaptobenzothiazole is used instead ofZ-mercaptobenzimidazole required by this invention, resultant heat-agingproperties are inferior to that attainable by this invention.

polyalkylene-polyamines in place of hexamethylenediamine carbamate whichwas used in Examples 9-16 and 18 were measured. The compoundedcomponents and the results of measurement are given in Table 3. It maybe seen from Table 3 that with any amine, magnesium TAB LE 2 Compoundingcomponents:

Epichlorohy drin polymer Tin stearate FEF carbon blackPhenyl-B-naphthylamine Nickel dibutyl dithiocarbamate-Hexamethylenediamine carbamate. 2-mercaptoimidazoline2-mercaptobenzimidazo1e.

2-mercaptobenzothiazole Heat-aging properties of vulcanizates: Tensildestrength (kg./cm. )after Example 12 days. Hardress (J IS) aiter 12 daysEXAMPLES 19-27 oxide system produces better heat-aging properties thanred lead system and that through joint use of sulphur,

The heat-aging properties (heating temperatures: 150 even better tensilestrength can be obtained even under C.) of vulcanizates made byemploying various types of Heat-aging properties of the vulcanizates:

Tenrsilie strength (kgJcmfi) after- Compounding components:

E pichlorohydrin polymer Tin stearate 2 FEF carbon blaok.. 40Hexamethylenediamine 1. 5 Triethylenetetramine DiethylenetriamineTrimene base.--

Red lead 6 Magnesium oxide Z-mercaptobenzimidazole 1 Sulphur.

15 days 65 85 58 73 57 74 58 77 78 7 EXAMPLES 28-33 TABLE Continued Theheat-aging properties (heating temperature: 160 Example number 34 36 37C.) of vulcanizates made by using thioureas in place Hardness (31s) m ofhexa-methylenediamine carbamate which was employed 0 d 64 65 53 61 2days 72 72 78 82 in Examples 9-16 and 18 as well as the effect ofsulphur 5 4 days 71 71 77 81 addition were measured in the same manner.The com- 333:" g 3g 3g pounded components and the results of themeasurement 12 ds sIIIII s 85 so are shown in Table 4.

TABLE 4 Example Compounding components:

Epichlorohydrin polymer 100 100 100 100 Tin stem'ato 2 2 2 FE]? carbonblack 40 40 40 2 2 -methylene bis (4-methyl-6-tert-buty1phenol) 2 2 2Ijlbutyl thimn'an 1 1 1 Thiour Red lead 5 5 Magnesium oxide.- 52-mereaptobemimmnmln 1 1 1 Sulphur 1 Heat-aging properties of thevuleanizates:

Tensile strength (kg/em!) after- 0 day 130 100 161 151 126 127 2 days 72211 100 131 s1 s7 4 days 65 s2 82 131 67 82 6 days... 40 81 61 so 51 718days- S 73 90 3o 67 Elongation (percent) after- Oday 490 820 480 890350 360 2 days.--. 280 300 160 130 90 70 4 days 280 280 140 120 so 50 6day 290 280 120 100 70 40 8 days... s 280 100 70 70 30 Hardness (JIS)after-- 0 day 58 5e 61 59 72 71 2 days.- 62 G8 72 76 76 82 4 days--. 7072 so 76 84 6 days-- 56 71 82 74 88 8 days... 8 60 84 72 90 EXAMPLES34-37 What is claimed is:

In addition to the respective compounded components gg z i i25 ig s inExamples 10, 12, 14 and 16, sulphur was added in the 40 t d g i e p yquantity of one part by weight, and the heat-aging propr 6 up cofnsls 1f h d d erties (heating temperature: 160 C.) of the vulcanizates (9)omolio ymer? i g z 1 a t obtained in the same manner were measured. Theresults 11 a copo ymer o 6P1 a o y rm a are given in Table 5. Thecomparison between the results 3: m gf monomer copo ymenza c of Table 5and the respective examples employing the I b 0 1 if b ht f t 1 ddifferent quantities of Z-mercaptobenzimidazole in Ex- 45 1 y Welg 0 ieasft one compoun amples 10, 12, 14 and 16 shows that the heat-agingpropf g grolllp 00.11818 Hg 0 erties can be remarkably improved bysulphur addition. 9 p0 ya y 9 yammes BL (11) alkylenediamme carbamates,and TA E 5 (iii) thioureas with the following general formula Examplenumber 34 35 36 37 50 Z-meroaptobenzimidazole, parts by weight 0t 4 0.8 1. 2 2. 0 S Heat-aging properties of the vulcanizates: R R

Tensile strength (kg/cm?) after- Oday 161 166 158 149 2 days- 121 151 4days.- 97 137 R R 6 days-- 92 127 55 9 days.- 34 73 days 36 58 k 1Elongatioupemnoagteh wherem each R can be hydrogen or an al y 0 day 660650 7 2 days 210 group of 1 no 4 carbon atoms and at least one 4 y 240170 'R 15 hydrogen, 6 days 240 60 (0) 1-20 parts by weight of magnesiumoxide; and 9days-. 210 12 days 74 an (d) 0.2-5 parts by weight ofZ-mercaptobenmmuiazole.

3 24 22 2. A vulcanizable composition according to claim 1 2 days 30 5o62 105 wherein the alkylenediamine carbamate is hexamethylene- 4 days 2338 49 87 6 days 21 37 50 84 diamme carbamate.

9 days 3 25 30 e1 6 3. A vulcamzable composition wh1ch comprises:

--------- 5 (a) 100 parts by weight of at least one polymer selectedfrom the group consisting of:

(i) a homopolymer of an epihalohydrin, and (ii) a copolymer ofepihalohydrin and at least one monoepoxy monomer copolymerizabletherewith; (b) 0.1-10 parts by weight of at least one compound selectedfrom the group consisting of:

(i) polyalkylenepolyamines, (ii) alkylenediamine earbamates, and

(iii) thioureas with the following general formula R\ S /R /NIN\ R Rwherein each R can be hydrogen or an alkyl group of 1 to 4 carbon atomsand at least one R is hydrogen;

(c) 1-20 parts by weight of magnesium oxide;

((1) 0.2-5 parts by weight of Z-mercaptobenzimidazole;

and

(e) 0.1-5 parts by weight of sulphur.

4. A vulcanizable composition according to claim 3 wherein thealkylenediamine carbamate is hexamethylenediamine carbamate.

5. A vulcanizate produced by a process which comprises heating thevulcanizable composition of claim 1.

6. A vulcanizate produced by a process which comprises heating thevulcanizable composition of claim 2.

7. A vulcanizate produced by a process which comprises heating thevulcanizable composition of claim 3.

8. A vulcanizate produced by a process which comprises heating thevulcanizable composition of claim 4.

References Cited UNITED STATES PATENTS Jarboe 26045.8 Langsdorf, Jr. etal. 26067 Chevassus 26045.75 Willis 26045.75 Inagami et al. 260-45.9Robinson et a1 26045.75 Chenicek 260800 Schlesmann et al. 26032.6Vandenberg 2602 Robinson, Jr. 260795 Bogemann et al. 260800 Robinson, Jr2602 Green et a1. 2602 Logan, Jr. 264236 DONALD E. CZAJA, PrimaryExaminer 20 R. A. WHITE, Assistant Examiner US. Cl. X.'R.

$222? 4 1 UNI E .I FICE CERTIFICATE CORRECTION Patent No. 3,790,524 vDated Februarv 5.. 1.974

Inventor-(s) Yoshiomi Saito eta],

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below Column 2,iine 48 cha nge "2 4" to 2 .4 4 Column 4, Table l, line 7 change "1.4"to 1.5

Column 4, Table l, vline 7 ch -ahge "l '-.0 I to 1.5

Column 5, Table :2,

the Elongation (oe rcent efter 'section on the 4 days line, change thesecond occurrence of "190" to Column 7, Table 4-, line 8 4 change "2,2-methylene" to I 2,2'-meth y lene Column 7, Table 4, line 18 change"211 to 112 Signed and sealed this 17th day' of December 1974.

(SEAL) Attest: 7

McCOYM. GIBSONJR. C. .MARSHALL 'DANN Attesting Officer Commissioner ofPatents

